Chronic obstructive pulmonary disease (COPD) is a major cause of global morbidity and is projected to become the third leading cause of death in the world by 2020. In Veterans, the prevalence is high; in VISN1 in FY 2012, 9% of outpatient Veterans had the ICD-9 diagnosis of COPD. In COPD, shortness of breath leads to physical inactivity and significant disability. A growing body of knowledge has identified physical activity and exercise as a modifiable factor that may impact COPD-related morbidity and mortality. Epidemiological and cross-sectional studies have shown that persons with COPD who are more physically active have better functional status and are less likely to be hospitalized and to die. A higher daily step count, when directly measured, is associated with lower risk of acute exacerbations (AEs) and mortality in COPD, independent of lung function. Despite the potential benefits, there have been few interventions to increase walking in persons with COPD. Although supervised pulmonary rehabilitation programs improve exercise capacity, they are not accessible to all who could benefit from them and have low adherence rates. Novel interventions that incorporate strategies for behavioral change and that are accessible, individualized, and sustained are needed to promote physical activity in persons limited by COPD. Funded by a RR&D CDA-2 (Dr. Moy), we have developed and piloted a novel exercise intervention that combines a website with a pedometer to promote walking in persons with COPD. The program, Every Step Counts (ESC) for Lung Health, accurately monitors walking, provides iterative feedback and individualized goal-setting, and delivers education and motivation. We propose a 2-arm randomized, controlled trial to study the efficacy of ESC to improve exercise capacity in persons with COPD, compared to usual care (verbal and written instructions to exercise). Primary Aim: Determine the efficacy of the ESC intervention to increase 6-minute walk test (6MWT) distance. Secondary Aims: Estimate the effect of the ESC intervention on (a) health-related quality of life (HRQL), as measured by the St. George's Respiratory Questionnaire (SGRQ), (b) dyspnea, (c) inflammatory biomarkers C-reactive protein (CRP) and interleukin-6 (IL-6), (d) risk for AEs and COPD-related hospitalizations, and (e) engagement in physical activity as measured by daily step count. 185 subjects will be enrolled for a total of 12 months, with the interventional phase being 6 months followed by an observational phase of 6 months. Subjects will be randomized (1:1 ratio) to one of 2 arms: (1) verbal and written instructions to exercise at home (usual care) or (2) usual care plus pedometer and Internet- mediated walking program. Subjects will perform 6MWTs, complete questionnaires, and have blood drawn at clinic visits at baseline, 3, 6, and 12 months. Telephone contact will occur at 9 months. AE history and daily step count will be assessed at each contact. Analysis of variance will compare 6MWT distance in the intervention and usual care group at 6 months. Multivariate regression models will assess 6MWT distance as a function of treatment group, adjusting for baseline 6MWT distance, study site, season of enrollment, and any unbalanced baseline characteristics. We hypothesize that persons randomized to ESC will have greater 6MWT distance at 6 months, compared to persons in the usual care group. We also hypothesize that persons randomized to ESC will have greater improvements in HRQL, dyspnea, daily step counts, and greater decreases in levels of inflammatory biomarker and risk for AEs and COPD-related hospitalizations, compared to control. Our intervention has the potential to (1) bring an exercise program to the vast majority of persons with COPD who cannot go to a hospital-based pulmonary rehabilitation program, (2) improve the effectiveness of current rehabilitation programs by sustaining long-term exercise, and (3) become an effective and integral part of COPD self-management programs. Ultimately, the intervention could decrease risk of hospitalizations, AEs, and COPD-related morbidity and mortality.